Hydroplane hull



July 9, 1935. E, w EASTHOPE 2,007,598

HYDROPLANE HULL Filed May 29, 1934 lNVENT'OR ERNEST WILLIAMS EAsTHoPE Patented July 9, 1935 UNITED STATES PATENT OFFlCE 2 Claims.

said air as an auxiliary means in raising. the

after step of the hull above the waterline when travelling at speed, whereby the skin friction at the after step is changed from that caused by water to the hull surface to air to the hull surface, thereby enabling the hull to be propelled at a higher speed per unit of power than before, and to convert the frontal air resistance 7 into useful power.

The invention consists essentially of a hull having forward and after steps so arranged as to permit frontal air encountered in travelling to be conducted below the bottom of the boat to a point aft of the forward step, as will be more fully described in the following specification and shown in the accompanying drawing, in which:

Fig. 1 is a side view of the hull part in section.

Fig. 2 is a transverse sectional view taken on the line 2-2 of Figure 1. 1

Fig. 3 is a transverse sectional view taken on the line 3-3 of Figure 1.

Fig. 4 is a side view of a modification showing part in section. v

In the drawing like characters of reference indicate corresponding parts in each figure.

The numeral l indicates generally a hull having side walls 2 and a bottom wall 3 terminating at its forward end in a bow 4 and at its after end in a step 5.

Adjacent the forward end of the hull, a forward step. Bis formed, which extends across the mid-section of the hull only, as shown in Figure 2, and extending forward from the base of this step is a front plane I which is bounded on its sides by walls 8, so as to provide a hollow structure 9 below the line of the bottom wall 3v to add to the buoyancy of the forward part of the hull, besides forming the forward plane.

The side walls 2 are extended downward below the bottom walls 3 and the plane 1, and are extended throughout the full waterline of the hull when elevated to speed running position to form side boards l0. These side boards serve to confine the air passing under the bow 4 and direct it through ducts II, defined between the side boards l0 and the hollow structure 9, to deliver it to beyond the rearward step 5.

In the modification shown in Figure 4, the

forward plane 1 extends from one side board to the other and provides a duct I 2 which is of the full width of the bow 4 through which frontal air can pass without obstruction to points to the rear of said plane, the rear of the plane 1 form- 5 ing in effect a step 6 as in the structure shown in Figure 1.

In operation, the hull rests in the water with its stern and the hollow structure 9 immersed in the water to provide the necessary buoyancy. When the hull is propelled at speed it rides up onto the surface of the water by virtue of its plane surfaces and the frontal air resistance is converted into an air stream somewhat in excess of the atmospheric pressure and is directed through the ducts II to the stern, the air pressure becomes cumulative by virtue of the progressive constriction of air space towards the stern and in orderfor such air to escape it exerts an upward pressure under the after step 5 and downwards onto the water below, so that the step is lifted out of substantial contact with the water'and the friction is correspondingly reduced, thus enhancing the speed of the hull.

In the modification shown in Figure 4, the front plane is of the full width of the hull at its forward end and the frontal air passes over it and accumulates a pressure as before described aft of the forward step.

It will be obvious that changes of disposition of the frontal air ducts may be made, for instance hollow structures 9 may be disposed adjacent the side walls with a single duct ll between them, or cowls may be provided in the forward deck to deliver air aft of the forward step.

What I claim as my invention is:

1. A speed boat hull having side walls, a bow, bottom walls and a forward and an after step, side boards extending downwards from the side Walls to below waterline when the hull is planing, said forward step extending less than the distance between the side boards and a longitudinal duct extending on both sides of the forward step to the rear thereof. 7

2. A speed boat hull having substantially parallel side walls extending downwardly below the water line, a forward step spaced from both side walls to provide air ducts, and a rear step extending from one side Wall to the other.

ERNEST WILLIAMS EASTHOPE. 

